Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/23/18
Area Forecast Discussion
National Weather Service Wakefield VA
1042 PM EDT Fri Jun 22 2018
A frontal boundary located just north of the Virginia North
Carolina border early this morning, will gradually lift back
north as a warm front later today into Saturday morning. A cold
front will drop across the area Sunday night into Monday
.NEAR TERM /THROUGH SATURDAY/...
As of 1030 PM EDT Friday...
Latest analysis reveals quasi-stationary boundary draped across
south central VA back into W VA/S WV. Weakening upper low over
the Ohio Valley continues to gradually lift ENE toward the
interior northeast. Several shortwaves pinwheeled east across
the northeast/Mid-Atlantic region, with convection developing
largely as anticipated by the ARW and Time-Lagged HRRR this
afternoon. Several strong to severe storms across central and SE
VA have given way to a second round of showers producing locally
heavy rainfall across the local area. Have dropped Flash Flood
Watch across piedmont, with showers tapering off over western
tier of the CWA.
As for the overnight, potential for heavy rain continues into
the early morning hours, but should diminish after 06-08z. Low
clouds and patchy fog, with areas of fog west of I-95. Early
morning lows in the 60s to low 70s.
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
As of 345 PM EDT Friday...
The frontal boundary will lift north of the area by Sat
morning. The highest Pops will shift to the northern counties
late tonight into Sat morning. SSW winds will pick up across the
the region Sat aftn. This along with a mix of sun and clouds
will push temps back into the upper 80s to lower 90s over most
areas. The heat index across southeast VA and northeast NC will
run around 100-102 degrees with mid to upper 90 heat indices
elsewhere. A shortwave trough is progged to cross the region in
the aftn/evening that could touch off a line of mainly diurnally
driven tstms. A sfc trough/weak cold front will move acrs the
area late Sat night thru Sun morning, with an actual cold front
then dropping acrs the region Sun night into Mon morning. Have
maintained chance PoPs with the trough overhead possibly kicking
off scattered showers/tstms. Highs on Sun in the upper 80s to
lower 90s. Monday will be dry and cooler behind the front.
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
As of 340 PM EDT Friday...
A ridge of high pressure builds in from the north on Tuesday as
a cold front and rain exit well to the south. This will provide
drier and cooler weather with afternoon highs in the low to
middle 80s. Dewpoints in the lower 60s will aid in making
Tuesday even more pleasant...much different than the upper
70/near 80 degree dewpoints we have been experiencing.
Mid-level troughing arrives as high pressure moves offshore
Wednesday, and the GFS tries to spark showers and thunderstorms over
the northwest corner of our CWA in the afternoon. The EURO keeps wet
weather slightly further west. Like most rain events this time of
year, these appear to be diurnally driven, dissipating by late
evening. Highs Wednesday will return to the upper 80s. Models
diverge in solutions regarding timing/placement of rain Thursday and
Friday, but expect better chances mid-morning Thursday and again
Temperatures by Thursday will warm into the lower 90s and push the
mid 90s by Friday. With southerly winds in play, expect muggy
conditions and nighttime temperatures in the lower 70s.
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
As of 800 PM EDT Friday...
Am watching two areas of t-storms as of 800 PM this evening. One
line extends from ~30 miles southeast of RIC to Isle of Wight
County, VA. This line will likely impact PHF (and the southern
edge could clip ORF). Expect gusty winds to 30-35 kt and brief
IFR visibilities with this line of t-storms. Another area of
showers/t-storms located from near Lynchburg south to the VA/NC
border is moving NE and could possibly impact RIC between
02-05z. Accounted for this with a TEMPO group. SBY/ECG should
remain dry for through at least the next few hours (less than a
30% chance of t-storms at SBY/ECG through 03z).
In addition to the t-storms, IFR ceilings are being observed in
RIC/SBY with MVFR conditions at PHF. Expect IFR CIGS to continue
through most of the night at RIC/SBY before improving Saturday
morning. CIGS could drop to IFR at PHF overnight, but not enough
confidence to include in the TAF. There is a chance of some patchy
MVFR fog overnight at RIC/SBY/PHF. Scattered aftn/evening
showers/tstms will be possible on Saturday and Sunday. Drier
conditions potentially arrive early next week.
As of 330 PM EDT Friday...
Went ahead and extended the SCA`s for the rest of the Ches Bay
(except mouth) based on latest wind gusts aoa 20 kts on back
side of the frontal boundary located along the James River to
ORF/VA beach. This boundary progged to meander across the waters
today before lifting back north as a warm front late tonight and
Sat morning. Expect diminishing winds once the onshore E-SE winds
shift back to the south. This could be as early as this afternoon
across the southern Ches Bay but kept the headline up through 20Z
due to the uncertainty. Seas slow to respond to the onshore
winds, bust expect them to reach arnd 5 ft across the northern
coastal waters. Kept the SCA ending time over the coastal waters
as late tonight as I expect a several hr period of seas blo 5
ft Sat morn before bumping up again later in the day.
The southerly flow returns Saturday as the warm front lifts
north of the waters. A Small Craft Advisory may once again be
needed Sat night due to a strong SSW push and seas arnd 5 ft.
RIC received 7.39 inches of rain since midnight. This is the
second all time daily rainfall record at RIC. Anotehr round of
showers is expected but will need to see how much rain occurs
by midnight LST (1 AM EDT). The all-time daily rainfall record
at RIC is 8.79 inches set on August 12, 1955 associated with
MD...Coastal Flood Advisory until 3 AM EDT Saturday for MDZ021>023.
VA...Flash Flood Watch until midnight EDT tonight for VAZ064-
Coastal Flood Advisory until 3 AM EDT Saturday for VAZ075-077.
MARINE...Small Craft Advisory until 4 AM EDT Saturday for ANZ650-652.
Area Forecast Discussion
National Weather Service Albany NY
922 PM EDT Fri Jun 22 2018
A storm system will move from the Ohio Valley tonight towards
the Northeast for tomorrow, bringing on and off rain showers and
isolated thunderstorms to the region, along with cloudy skies
and cool temperatures. Although this storm will move out for
Sunday, another cold front will keep the threat of showers and
thunderstorms around, mainly for Sunday afternoon. Drier weather
is expected for the start of next week, with temperatures
moderating above normal through the week.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 920 PM EDT...Closed off upper level low is located over
western Indiana and is starting to slowly shift eastward
towards our area. Ahead of this feature, swirling bands of high
clouds have been moving across our area. Some lower and thicker
clouds are finally starting to make progress towards our area
from Pennsylvania and New Jersey, as low level warm advection
increases thanks to a stregthening low-level jet.
CLouds look to increase and become thicker from south to north
through the evening hours, but it should stay precip-free
through about midnight. Afterward, hi-res model guidance (such
as the 3km HRRR and NAMNest) suggest spotty areas of light rain
and showers will be lifting from southwest to northeast thanks
to isentropic lift in place. These showers look to be mainly
from I-90 on southward, but some locations may see the ground
wet by daybreak Saturday.
With the clouds and showers around, temps won`t be as cool as
the past few nights, with lows mainly in the mid to upper 50s.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
During the day Saturday, the upper level low will be lifting
towards the Northeast. However, it will be opening up and
weakening as moves within the southwest flow aft and runs into
ridging in place. The surface low pressure area will also be
weakening as it moves towards western New York, although a
secondary area of low pressure looks to be developing across the
mid-Atlantic states along the storm`s warm front. With this
setup in place, our area will remain on the northerly and cooler
side of the storm system, with the light low-level flow out of
Showers will continue to increase in coverage through the
day. Although it won`t be raining the entire day, it will be on
and off and models still disagree on which areas will see the
highest concentration of showers. Most of the precip looks
fairly light, although cannot rule out some moderate bursts from
time to time. There could be a rumble of thunder, but any
instability will be elevated due to the strong inversion around
850 hpa and no storms will be strong/severe.
With the clouds and showers around, temps will only max out in
the 60s across the region, with even some upper 50s for the
Adirondacks and Greens.
On Saturday night, the secondary low pressure area will be
taking over as it lifts towards eastern New England. As a
result, showers look to diminish in coverage, although still
can`t rule one out. It will stay cloudy and damp and with the
recent rainfall, there will probably be a lot of fog and low
clouds remaining in place through the overnight hours with lows
in the upper 50s to low 60s.
On Sunday, the next system will quickly be approaching from the
northwest, as another shortwave and surface cold front moves in
from the Great Lakes. Another round of showers look to occur
with this boundary, mainly for the afternoon and early evening
hours. With some breaks of sun expected ahead of the front,
there could be some surface-based instability and some thunder
will be around as well, especially by late in the day, as the
approaching shortwave allows for better height falls and a more
favorable setup for thunderstorms. PWATs will remain fairly
high, so any thunderstorm will be capable of heavy downpours,
but weak lapse rates and limited 0-6 km shear should prevent any
storms from getting too tall or strong. With some sunshine,
highs should reach into the 70s, with even some low 80s for far
Showers and any thunderstorms will quickly diminish on Sunday
evening with the passage of the cold front and it should start
drying out for Sunday night. Lows will be in the 50s to low 60s
with decreasing dewpoints a light northwesterly breeze.
.LONG TERM /MONDAY THROUGH FRIDAY/...
The long term forecast period will begin with a low pressure system
departing to our east with some lingering showers possible primarily
over western New England. High pressure will build in mid week with
a low pressure system approaching from the west during the mid-to-
late week time period.
Monday and Tuesday...As a low pressure system departs to our east
and cyclonic flow overhead, there will be a slight chance for some
lingering rain showers over the region with higher confidence over
the New England zones. Strong upper ridging and surface high
pressure will build in from the northwest on Tuesday and linger into
Wednesday. Warm temps in the upper 70s to low 80s and sunny
conditions will accompany the high pressure. How strong and how much
blocking the aforementioned high provides will be a key player in the
timing of the approaching front on Wednesday into Thursday.
Wednesday through Friday...Clouds will increase on Wednesday with an
approaching shortwave and associated low over the Great Lakes. The
associated cold front looks to progress through the region somewhere
in the late Wednesday into early Thursday time period. The timing
will be crucial for thunderstorm potential and for now looks
unfavorable with an overnight passage as suggested by the GFS (the
ECMWF being even slower). With the low approaching and a strong high
off the East Coast there will be a good pressure gradient and low
level jet in place as well. This system will have to be monitored
as we approach mid next week.
As the system departs to our east conditions should start to dry
out late Thursday or early Friday as some weak mid-level height
rises push into the region. Global guidance is suggesting some
Atlantic moisture advecting northward into the region with southerly
flow and possibly a weak boundary moving through the region on
Friday so have kept slight chance to chance PoPs in the forecast for
now. The southerly/southwesterly flow will like usher in some
unseasonably warm temperature into the mid to upper 80s by the end
of the week.
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
High pressure exiting east and a frontal system approaching from the
west. Mid and high clouds are spreading northeast through tonight.
The leading edge of showers will move into the KPOU area before
sunrise Saturday and by mid morning at KALB, KPSF and KGFL.
Including visibilities around 6SM by 07Z at KPOU and by 15Z to
18Z at KALB, KGFL and KPSF. Steadier showers could begin at
KPOU by 15Z but will take until midday or early afternoon at
KALB, KGFL and KPSF. Ceilings will drop to 1500 feet at KPOU
and will likely stay between 2500 and 3000 feet at KALB, KGFL
Winds will be light and variable at 6 kts or less tonight then
east to southeast at 5 to 8 kts on Saturday.
Saturday Night: High Operational Impact. Likely SHRA...FG...TSRA.
Sunday: High Operational Impact. Likely SHRA...TSRA.
Sunday Night: Moderate Operational Impact. Chance of SHRA.
Monday: Low Operational Impact. Slight Chance of SHRA.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Low Operational Impact. Slight Chance of SHRA...TSRA.
Cloudy and damp conditions are expected over the weekend as an
area of low pressure moves across the region for Saturday and a
cold front moves through for Sunday. RH values will only fall as
low as 60 to 75 percent on both Saturday and Sunday. Most of the
region should see in excess of a quarter inch of rainfall, with
totals generally between one half inch and one inch of rain by
Sunday evening. East to southeast winds will be 5 to 10 mph on
Saturday and will be switching to the west to southwest at 5 to
10 mph on Sunday.
No hydro problems are expected over weekend and into next week.
Most of the entire Hydro Service Area /HSA/ is under abnormally
dry conditions according to the latest US Drought Monitor.
As a storm system moves across the region, periods of showers
and a few thunderstorms are expected between late tonight and
Sunday evening. Basin average rainfall amounts are expected to
range between half an inch to an inch, though locally higher
amounts are possible with any thunderstorms.
Minimal rises are expected on the waterways. Dry weather
returns Monday afternoon into the midweek before another cold
front moves across the region for Wednesday into Thursday with
some scattered showers or thunderstorms.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
Area Forecast Discussion
National Weather Service La Crosse WI
608 PM CDT Fri Jun 22 2018
.SHORT TERM...(Tonight through Saturday)
Issued at 145 PM CDT Fri Jun 22 2018
Mostly cloudy skies prevailed across the region this afternoon.
Isolated showers were moving west southwestward across southern
Wisconsin into east-central Iowa. A few of the showers could make it
into southern portions of Grant County over the new few hours.
Otherwise, skies will become partly cloudy tonight. The combination
of clearing skies and light winds should allow for some patchy
valley fog to form. Still some uncertainty if areas of dense fog
would form due to short nights, cloud cover and light northerly
winds. Evening shift will need to monitor to see if dense fog would
need to be introduced to the forecast.
On Saturday, partly cloudy skies should start the day with clouds on
the increase later in the day. Temperatures should be a few degrees
warmer than today, thus raised high temperatures a few degrees. At
La Crosse, did not go quiet as warm as the latest numerical guidance
which seemed a little bit too warm compared to readings across the
region this afternoon.
.LONG TERM...(Saturday Night through Friday)
Issued at 145 PM CDT Fri Jun 22 2018
For Saturday Night into Sunday...will be watching an area of low
pressure and warm front lifting northeast toward the region.
Increasing warm air advection and 850mb moisture transport should
generate/spread isolated to scattered showers and thunderstorms into
A stronger area of low pressure lifts slowly northeast toward and
eventually into the area Monday night into Tuesday night for the
likelihood of more showers and storms. Precipitable water values
also increase into the 1.5-2 inch range, so may have to watch for
some heavier rainfall with this system. This could lead to some
hydrology issues with rivers running high or rivers that have
ongoing minor flooding.
For Wednesday through Friday...both the GFS/ECMWF build upper level
ridge into the region. The ECMWF is much more amplified than the
GFS. GFS also brings some convection through the ridge whereas the
EC keeps things mainly dry and much warmer. Will run with a
consensus at this point.
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 608 PM CDT Fri Jun 22 2018
VFR conditions expected through the period as a weak area of high
pressure drifts east across the region through Saturday afternoon.
With the recent rains, some concern for fog development overnight,
especially in the river valleys. Clearing skies and light winds
through a relatively deep layer would favor fog development while
the short night and both the 22.18Z NAM and 22.21Z RAP forecast
soundings not showing saturation at the surface would argue
against fog development. For now, have left the mention of VCFG in
for KLSE while decreasing the coverage wording in the grids to
just patchy with a minimal visibility restriction.
Issued at 145 PM CDT Fri Jun 22 2018
Area rivers are running high with some minor flooding occurring or
forecast in places. Concern is increasing for more flooding heading
into early next week as a couple weather systems impact the area.
Vigorous system rotating through the region Monday nigh through
Tuesday night looks to have the biggest impact with precipitable
water values increasing into the 1.5-2 inch range. Will be keeping a
close eye on the evolution of this system and potential for flooding.
Area Forecast Discussion
National Weather Service Wilmington NC
930 PM EDT Fri Jun 22 2018
Hot and humid weather with isolated thunderstorms will continue
through the weekend and into Monday. Heat advisories are
possible Sunday and Monday. A cold front will cross the area
late Monday and Tuesday bringing a good chance for showers and
thunderstorms. Much cooler weather will follow for the middle
of next week before temperatures rebound above normal by next
.NEAR TERM /THROUGH SATURDAY/...
As of 930 PM Friday...I`ve boosted PoPs to 30 percent from
Hartsville to Bennettsville and Red Springs due to a line of
thunderstorms stretching from Newberry to Saluda, SC and moving
northeastward. Latest HRRR shows this area of convection
surviving in at least a broken line state as it moves into this
portion of the Sandhills between 11 PM and Midnight. The bulk of
this activity should remain just north of the city of Florence
assuming it remains on a linear trajectory. No other
significant changes. Discussion from 730 PM follows...
Unless an isolated shower can manage to overcome the dry air
aloft across the I-95 corridor late this evening as indicated by
several recent HRRR runs, the overnight period should remain
dry. A modest low-level jet (20-25 kt at 925 mb) should keep
surface winds from decoupling for most locations, with lows
expected to remain in the very muggy 75-80 degree range. Our
forecast low of 80 in Southport, should it verify, would be the
second night in a row with an 80 degree low temperature there.
Mercer Pier at Wrightsville Beach had an 81 degree low last
night! Changes to the forecast were very minor. Discussion from
300 PM follows...
750-600 mb capping keeping a lid on deep convection so far.
Along the sea breeze, and an inland thermal trough are the
favored locations for an updraft to pop through but longevity
would be limited. We are seeing enhanced cumulus in these
regions, and the Sandhills trough appears lined up well with
weak vertical circulations aloft, along a precipitable water
gradient and as such a few storms could pop here.
Heat Advisory posted for Williamsburg and Georgetown counties
until 6 PM today, where temperatures may climb several more
degrees. Saturday falls shy of heat headlines at this time, but
increasing mid-level moisture and high SBCAPES should allow
isolated to scattered TSTMS to develop Saturday.
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...The mid level pattern will be almost due
west to east for Sunday and this will lead to probably the
hottest day of the year. With a deep downslope flow and a sea
breeze not making much inland progress expect wide coverage of
middle and upper 90s. By late Sunday night into early Monday a
decent shortwave buckles the flow with a front pushing across or
in the process of pushing across by the end of the period.
Expect good coverage of convection with this feature as well. As
for pops for Sunday, I walked back the values somewhat due to
somewhat unfavorable profiles.
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM Friday...One last very hot and humid day forecast
for Monday but a change is coming. That change is due to a
strong cold front which will drop slowly southward across the
area Monday night into Tuesday, and may stall briefly before
pushing further south and washing out by Wednesday. This will
bring a good chance for showers and thunderstorms Monday night
and Tuesday, with heavy rain possible. Although this front will
dissipate into Wednesday, cool surface high pressure and broad
troughing aloft will keep temps much cooler through late week
before ridging develops again from the west with a possible
return to significant heat by the end of the week. With the high
pressure in place and cooler temperatures, convective potential
will be decreased Wed-Fri, with just isolated tstms possible
during the aftns. Highs Monday will climb well into the 90s with
heat advisory criteria heat index values possible. Temps Tue-
Thu will fall to more seasonable levels for both highs and lows
before warming again to above normal at the end of the period.
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Upper low will slowly move north northeast through the forecast
period. Overnight, little to no fog expected the a moderate
southerly wind, keeping the atmosphere fairly mixed. Saturday,
convection will be hard to kick off, but it looks like a spoke of
energy from the upper low will interact with the sea breeze tomorrow
afternoon. Pretty strong southwest flow expected.
Extended Outlook...Mostly VFR. Mainly afternoon showers and
thunderstorms each day with short duration restrictions
possible. A cold front will bring a better chance for showers
and thunderstorms Monday.
NEAR TERM /THROUGH SATURDAY/...
As of 930 PM Friday...The CORMP buoy a couple miles off Sunset
Beach has been reporting consistent wind gusts of 20-25 knots
for the past couple of hours. CCU pier observations from Myrtle
Beach and North Myrtle Beach confirm 15-20 knot breezes even on
the coast. I`ve updated the marine forecast to maintain these
stronger wind speeds for the next several hours before winds
diminish a bit overnight.
The CORMP `harbor` buoy south of Southport is now reporting 3.5
foot seas as these stronger winds have had time to work on the
ocean surface. Seas of 2-4 feet should continue overnight.
Discussion from 730 PM follows...
Seabreeze-enhanced winds gusting over 20 knots at times should
diminish near shore this evening, but the synoptic wind will
continue at a solid 15 knots with gusts near 20 knots all night.
Seas continue to build, and should reach 3 to locally 4 feet
overnight. Changes with this forecast update were very minor.
Discussion from 300 PM follows...
SW winds ongoing, generally 15 kt, with occasional gusts to 20
kt. Winds will pick up late Saturday a bit and an `Exercise
Caution` headline may be needed beyond this period. Seas around
3 ft, but up to 4 ft outer waters at times, especially Saturday
afternoon. Dominant wave energy, S waves 3 feet at 5 seconds, so
bumpy conditions can be expected. Radar updates are encouraged
as scattered TSTMS will prevail Saturday.
SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...Fairly brisk winds across the waters
through the period via good low level jetting and an approaching
front very late in the period. Expect a southwest flow of 15-20
knots through the period. Significant seas should be 2-4 feet
but some five footers could wander into the spectrum from time
to time especially late in the period.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 300 PM Friday...A cold front will drop slowly across the
waters Monday night through Tuesday, causing winds to turn from SW
early, to NE at 10-15 kts during Tuesday. This front will sag
southward and then dissipate into Wednesday as high pressure
elongates offshore. This drives winds to a more easterly direction
on Wednesday, while maintaining those 10-15 kt speeds. Wave heights
will be generally 3-4 ft through the middle of next week. However, a
variety of wave groups will exist due to the fluctuating winds, so a
confused spectrum is likely at times the first half of the period
before an easterly 5-sec wind wave becomes dominant.
SC...Beach Hazards Statement from 6 AM EDT Saturday through
Saturday evening for SCZ054-056.
NC...Beach Hazards Statement from 6 AM EDT Saturday through
Saturday evening for NCZ106-108.
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
856 PM CDT Fri Jun 22 2018
Updated for evening discussion.
The majority of convection has diminished across the region with
the loss of heating. Went ahead and canceled the watch a little
early. The HRRR is continuing to show the low level baroclinic
zone retreating to the north overnight, but showing nothing more
than a few showers that develop in the process. Have removed
marginal severe risk over the north overnight as convective
development looks to hold off until Saturday with most of it
staying just north of the forecast area./26/
Prior discussion below:
Through the day Saturday:
Solid convective cluster has finally taken shape over the
northwest portion of the forecast area in the last few hours, with
this cluster advancing steadily southeast toward the heart of the
region. Throughout the day convection has shown a tendency to
"back-build" into an impressive nose of warmth and moisture
advection aloft anchored over the Arklamiss Delta. Lately this
advection feature has opened up a bit and is less focused, aiding
the ability of convection to start propagating southeast.
Meanwhile, the cold pool from persistent convection over
northwestern zones throughout the day has generally advanced well
southwest of most vigorous convection, thus ensuring the bulk of
storms were "elevated" above the surface, reducing their
respective potential to produce severe weather.
Anyway, latest trends are increasing severe potential once again
into early this evening, especially over the western two-thirds of
current SVR watch # 197. The main risk through early this evening
will be damaging wind gusts, although some hail (and even a stray
and brief tornado) cannot be ruled out owing to seasonably
impressive low level shear. The SVR watch currently is set to
expire at 7 pm, but given trends it is certainly possible it may
have to be extended in time a few hours, at least south of I-20.
Flooding was a large concern north of I-20 over the Arklamiss
Delta, but the trend toward forward-propagation (i.e., movement)
is somewhat reducing the threat of at least major flooding.
Thoughts are that the convective cluster should exit the region to
the south/southeast by mid to late evening with a good deal of the
shower and storm ending in its wake.
However, latest expectations are that composite moisture
convergence and advection will increase well upstream (to the
west/northwest) of our region this evening in advance of another
vigorous storm cluster developing toward the Red River Valley.
There is some potential either this cluster, or another batch of
thunderstorms induced by this cluster, will progress east/south
down the re-orienting baroclinic zone and pass in the vicinity of
our northern zones late tonight through tomorrow morning. A
MARGINAL risk of severe thunderstorms was included in the graphics
and HWO to handle this threat, but due to a high degree of
uncertainty in this chaotic convective regime, there is some
chance the threat will be either removed later or even upgraded.
Tomorrow, by midday any storms passing through northern zones
should be largely to our east or lifting to the north, leaving are
region partly cloudy, seasonably breezy, and very humid. High
temperatures getting into the lower 90s (and approaching the mid
90s in a spot or two) should yield heat index value near or
exceeding the century mark over the majority of the area by the
afternoon. Currently thinking heat advisory thresholds will not be
met tomorrow so will continue to just highlight the heat stress in
the graphics and HWO. /BB/
Saturday night through the work week...
The story of the weekend into the work week will be that of
increasing heat and humidity. The upper trough will be to our east,
which will leave zonal flow and/or broad ridging across the area.
With moisture left in place, this will allow for heat stress issues
to begin to be a concern for much of the area on Sunday. In
addition, capping should allow for a decrease in shower/storm
activity. This heat concern will continue through much of the week
for entire area as high pressure will expand west from the Atlantic.
As heights rise, temperatures will also be increasingly warmer with
some locations seeing highs in the mid 90s. This, combined with
dewpoints in the mid 70s, will bring heat indices near 105 degrees.
In some instances, this threshold will be exceeded. Heat advisories
may be likely this week. One caveat to this may be the increased
potential for diurnal showers and storms through the week. For
residents planning outdoor activities, it will be wise to continue
to monitor the potential for higher heat indices through the week.
00Z TAF discussion:
Main concern this evening associated with scattered TSRA clusters
mainly along the I-20 corridor which should diminish early this
evening, but a few TSRA will continue to be possible as outflow
boundary moves into the HBG/PIB area in the next couple of hours.
Otherwise, expect VFR conditions until pre-dawn hours when
MVFR/IFR category stratus will develop, with lowest ceilings
mainly in the HBG/PIB area - expect this to gradually mix up to
VFR category ceilings by late morning into early afternoon.
Another disturbance could bring a few SHRA/TSRA to GLH/GWO area
mid/late Saturday morning. /EC/
.PRELIMINARY POINT TEMPS/POPS...
Jackson 70 93 74 93 / 13 9 3 7
Meridian 72 95 74 94 / 22 9 3 7
Vicksburg 70 93 74 93 / 6 8 3 8
Hattiesburg 74 94 74 93 / 16 10 3 11
Natchez 75 92 74 92 / 8 10 5 10
Greenville 70 92 75 92 / 8 27 6 5
Greenwood 72 92 74 91 / 10 23 6 7
Area Forecast Discussion
National Weather Service Little Rock AR
901 PM CDT Fri Jun 22 2018
Continuing to monitor development of a linear convective complex,
extending from south central Kansas, to the Texas panhandle. Some
overall weakening of this activity is still expected as it
approaches western sections of the forecast area. Have made minor
adjustments to near term forecasts to refine temporal resolution
of pop/wx forecasts.
.PREV DISCUSSION...(ISSUED 627 PM CDT Fri Jun 22 2018)
Forecasts will reflect expected evolution of MCS activity, most
likely to affect western sections between 06 and 10z.
PREV DISCUSSION...(ISSUED 259 PM CDT Fri Jun 22 2018)
SHORT TERM...Tonight Through Sunday
Model discrepancies continue to exist with the storm system set to
move into western Arkansas during the overnight and early morning
hours tonight. For the past few days models have been bringing the
system into northern Arkansas late Friday night and the coarser
models continue to do so today. However the HRRR has consistently
showed the precipitation weakening across northwest Arkansas and
trending further south...similar to the location where storms are
currently ongoing. If I was confident the HRRR would pan out, I
could see issuing a flash flood watch across the locations in
southern Arkansas where they have seen flooding today. However, will
hold off on issuing a flash flood watch at this time.
Stalled front over Arkansas will begin to pivot and lift back to the
north on Sunday. This will keep rain chances across the northern
third of the state. By late Sunday night the front will lift north
into southern Missouri and bring dry weather to the state Sunday
night and into Monday.
LONG TERM...Sunday Night Through Thursday
To begin the period, large upper troughing across the
Central/Northern Plains will begin ejecting to the northeast. While
shortwave trough energy associated with this feature will graze far
northeastern AR, subsidence from a building upper ridge to our south
should keep precip east of the area where better upper level support
Significant upper ridging across the SW CONUS will spread east with
time, with the center of the ridge effectively atop AR by late week
into next weekend. Strong subsidence will largely prevent thunder,
although isolated diurnal convection cannot be entirely ruled out.
Expect hot temps to continue, with highs ranging from the low 90s
north to mid/upper 90s south. Lows each night will remain in the low
to mid 70s.
Area Forecast Discussion
National Weather Service Blacksburg VA
1035 PM EDT Fri Jun 22 2018
A frontal boundary will drift slowly north tonight as a wave of low
pressure along it moves east. Scattered to numerous showers and
thunderstorms are expected across the region into tonight. The rain
may be heavy at times. Low pressure will move from the Ohio Valley
to the eastern Great Lakes Saturday, then eastward across New
.NEAR TERM /THROUGH SATURDAY/...
As of 1013 PM EDT Friday...
Flash flood watch for the piedmont cancelled early as heavy rain
and flood threat has ended for the night.
Atmosphere has been worked over but still some upper support to
our west, where upper low exists over the Ohio Valley. Enough
pockets of instability and deep moisture convergence to not
allow for a completely dry forecast overnight but coverage of
showers should be more isolated and not as strong in terms of
storms and heavy rain.
Pockets of fog will also form but stratus and mid level clouds
may keep fog limited in coverage.
Previous discussion from early evening...
Forcing continues for deep convection from the Alleghanys east
into the piedmont of VA along frontal boundary. Effective shear
is 40-45kts across the VA piedmont with 0-1km helicity around
150 m2/s2. As we head into the evening, expect some decrease in
intensity to the storms, but another hour or two of a threat for
damaging winds, and isolated spinups, though so far we have not
confirmed any tornado touchdowns.
Will keep the flash flood watch as is, but storms have moved
enough to keep flooding to minimum except minor urban flooding
Previous discussion from early afternoon...
Flash Flood Watch remain in effect until midnight for
A closed upper low over Indiana this afternoon will open up and
northeast tonight into Saturday. Numerous showers and thunderstorms
have developed this afternoon in the unstable air across our region.
SPC Mesoscale analysis at 18z showed Surface based CAPES from 1k to
2500 j/kg and LIs from minus 2 to minus 4 across our forecast area.
The Effective bulk wind shear still demonstrates a pocket of 30 to
40 knot this afternoon. SPC in the Day One Convective outlook
continued a slight risk of severe weather in our northeastern
portion of the forecast area with marginal risk elsewhere.
There remains a potential for supercells. Damaging winds, heavy
rains and hail are the primary threat with deeper convection.
Showers and thunderstorms will move east across our area
this afternoon into tonight. HiResW-arw-east and HRRR capture
the main band of convection quite well for this afternoon. The
NAM,GFS and ECMWF showed scattered storms moving east across the
region tonight. Spokes of energy associated with the upper low
may result in lingering showers overnight especially in the west.
Areas of low clouds and fog will develop overnight especially
where heavier rain falls this afternoon. Low temperatures tonight
will range from the upper 50s in the mountains to around 70 degrees
in the piedmont.
With the movement of the low pressure center northeast, the warm
front will continue to advance north Saturday with the cold front
pushing east. The cold front should move across our area Saturday
afternoon into Saturday night. Shortwaves rotating around the upper
trough will enhance convection. The Latest day 2 convective outlook
placed a marginal chance to our east and to our west. In any case,
expected scattered showers and thunderstorms again on Saturday.
High temperatures will vary from around 70 degrees in the northwest
mountains to near 90 degrees in the piedmont.
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 253 PM EDT Friday...
500MB heights rising Saturday night through Monday night. Flow is
zonal Saturday night and Sunday with more ridging by Monday. A 60
knot jet streak over the West Virginia and Pennsylvania Sunday will
provide some shear and upper diffluence during the afternoon and
Downsloping winds and 850MB temperatures across southern Virginia
and northern North Carolina will result in above normal temperatures
east of the Blue Ridge on Sunday. Will stay on the warm side of
guidance for maximum temperatures.
Confidence for all elements is average.
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 253 PM EDT Friday...
Upper ridge over the forecast area on Tuesday. Northern jet stream
remains progressive and models in decent agreement bringing the next
trough through the northeast United States on Wednesday and
Surface high pressure over the northeast and Mid Atlantic on Tuesday
will move offshore by Wednesday. This will mean a return of moisture
and a daily thunderstorm threat each afternoon and evening.
Potential for west to northwest surface to 850MB winds on Thursday
and Friday as seen on the ECMWF may limit areal coverage of
precipitation. Temperatures will be slightly above normal through
Confidence for all elements is average Tuesday and Wednesday and
below average for Thursday and Friday probability of precipitation.
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
As of 715 PM EDT Friday...
Expect showers/storms to impact LWB/ROA/LYH early thru about 1z,
maybe 2z LYH, the isolated threat overnight, with moisture laden
airmass leading to fog and low cig potential. Will be going with
at least MVFR vsbys at all sites, with lower vsbys across the
mountain taf sites. Confidence is medium on this as some mid and
higher level clouds and mixing may keep fog patchy/intermittent.
Will see the low stratus/fog erode by 12-14z, then VFR through
Sat afternoon. Storms fire up again in the afternoon, with best
chance over the mountains, so have VCTS there after 18z.
.Extended Aviation Discussion...
A cold front will finally sweep through the region Sunday with
improving conditions Monday and Tuesday. Isolated to scattered
MVFR showers and thunderstorms are possible Wednesday.
As of 200 PM EDT Friday...
The NOAA weather radio transmitter in Hinton, West Virginia that
is WXM72 and broadcasting at a frequency of 162.425 MHz is off
the air. Parts are on order to repair the transmitter, but there
is no known time of restoration. We apologize for any